1. Field of the Invention
The present invention relates to a storage device, a memory, terminal, a server, a server-client system, a storage medium, and a control device.
2. Description of the Related Art
Physical formatting is performed to use a magnetic disk incorporated in a magnetic disk device. Physical formatting divides a storage area of the magnetic disk into sectors of predetermined bytes to manage and locate the sectors for reading and writing. Japanese Patent Application Laid-open No. 5-62360 discloses a technology in which, when a bad sector (a sector in which an error rate will be equal to or greater than a reference value, and error correction will be disabled) is detected during physical formatting, the magnetic disk device performs slipping process thereto, and writes or reads user data on other sectors regarding the bad sector as unusable.
When, after physical formatting, a bad sector is detected at the time of storing user data, a magnetic disk device performs replacement process to store user data to be stored in a bad sector in an area previously secured on the magnetic disk instead.
Japanese Patent Application Laid-open No. 11-232046 discloses a technology in which, when data stored in a bad sector on a magnetic disk is transferred to an alternative sector, data in a plurality of sectors including the alternative sector is read all together to be stored in a memory. This suppresses a reduction in performance between a host computer and a magnetic disk device due to access to the alternative sector.
However, slipping process/replacement process is performed to a detected bad sector when or after physical formatting is performed and the bad sector is regarded as unusable in the conventional technology, thereby leading to a significant reduction in a capacity that can be used on a magnetic disk due to more bad sectors, which is directly associated with a reduction in a yield without satisfying a storage capacity defined by a specification of a device.
That is, when a bad sector is detected, there is a need to prevent a capacity that can be used on a magnetic disk from significantly reducing when a sector size (the number of bytes that can be recorded) is magnified from current 512 bytes to 1024 bytes, 2048 bytes, or 4096 bytes. Conventional slipping process gives a bad influence to a data transfer speed because a blank sector is physically present.